Transcriptomic Analysis of the Photosynthetic, Respiration, and Aerenchyma Adaptation Strategies in Bermudagrass (Cynodon dactylon) under Different Submergence Stress.

Zhongxun Yuan,Muhammad Arif,Jiajia Li,Zhi Dong,Changxiao Li,Xilu Ni,Xue Tan,Limiao Zhang

doi:10.3390/ijms22157905

Abstract

Submergence impedes photosynthesis and respiration but facilitates aerenchyma formation in bermudagrass. Still, the regulatory genes underlying these physiological responses are unclear in the literature. To identify differentially expressed genes (DEGs) related to these physiological mechanisms, we studied the expression of DEGs in aboveground and underground tissues of bermudagrass after a 7 d treatment under control (CK), shallow submergence (SS), and deep submergence (DS). Results show that compared with CK, 12276 and 12559 DEGs were identified under SS and DS, respectively. Among them, the DEGs closely related to the metabolism of chlorophyll biosynthesis, light-harvesting, protein complex, and carbon fixation were down-regulated in SS and DS. Meanwhile, a large number of DEGs involved in starch and sucrose hydrolase activities, glycolysis/gluconeogenesis, tricarboxylic acid (TCA) cycle, and oxidative phosphorylation were down-regulated in aboveground tissues of bermudagrass in SS and DS. Whereas in underground tissues of bermudagrass these DEGs were all up-regulated under SS, only beta-fructofuranosidase and α-amylase related genes were up-regulated under DS. In addition, we found that DEGs associated with ethylene signaling, Ca2+-ROS signaling, and cell wall modification were also up-regulated during aerenchyma formation in underground tissues of bermudagrass under SS and DS. These results provide the basis for further exploration of the regulatory and functional genes related to the adaptability of bermudagrass to submergence.

Highlights

Submergence inhibited the expression of genes related to the light and dark reaction stages of photosynthesis in aboveground tissues of bermudagrass, resulting in a decrease in photosynthetic products
Genes encoding the glycolytic key enzyme (Pgm, ALDO, gpmB, and pyruvate kinase (PK)), tricarboxylic acid (TCA) cycle (PDHA, MDH, and ACLY), and adenosine triphosphate (ATP) synthase (ATPF1D, ATPF1G, ATP1–2, ATP 6, and ATP 6B) were downregulated, suggesting that the respiration of aboveground tissues of bermudagrass was affected to a certain extent under submergence
The results show that a large number of genes involved in the sucrose and starch hydrolysis, glycolysis, TCA cycle, and oxidative phosphorylation of the underground part were up-regulated under shallow submergence (SS), actively maintaining the normal physiological activities of bermudagrass

Summary

Introduction

Climate change increases extreme rainfall and flood events, which impact the vegetation cover globally. Submergence stress has become one of the most significant global problems for vegetation deterioration. It has hampered social and economic development and has posed an increasingly severe threat to global ecological security. Many parts of the world are experiencing various degrees of submergence, including the water-levelfluctuation zones formed after the construction of artificial dams [1,2].

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Conclusion